In order to investigate the molecular properties of the type IV collagen metalloproteinase, we have obtained primary sequence information and using this data, have developed monospecific antibodies. The sequence inforaation identifies type IV collagen metalloproteinase as a unique enzyme with some homology to other extracellular matrix degrading metalloproteinases. Synthetic peptides generated using this sequence information were used to make anti-type IV collagenolytic metalloproteinase antibodies. These antibodies were used to investigate the mechanism of activation of the collagenase and to screen an expression library to obtain a cDNA clone.